Sulfur containing molding compositions, sulfur containing consolidated products, and method of making the same



May 2, 1950 Filed June 15, 1948 W22 ier lflb sorpizion J. G. MEILER ET Al 2,505,782

SULFUR CONTAINING MOLDING COMPOSITIONS, SULFUR CONTAINING CONSOLIDATED PRODUCTS, AND METHOD OF MAKING THE SAME 4 Sheets-Sheet 1 O Phei'zolic resin alone x H plus Sulfur A II I II u Phenolic Resin INVENTORS John 6. Me 1161- Karl B. Bollcr's Zev May 2, 1950 J. G. MEILER ET AL 2,505,782 SULFUR CONTAINING MOLDING COMPOSITIONS, SULFUR CONTAINING CONSOLIDATED PRODUCTS, AND METHOD OF MAKING THE 'SAME Filed June 15, 1948 4 Sheets-Sheet 2 Thickness SW61 Zirg O 5 IO [5 2o 25 I so as X: Phenolic Resin,

INVENTORS John 6. M21112! 6; Karl E. BoZZens'Zev WWW may 2, 1950 J. G. MEILER ET AL. 2,505,732

SULFUR CONTAINING MOLDING COMPOSITIQNS, SULFUR CONTAINING CONSOLIDATED PRODUCTS, AND METHOD OF MAKING THE SAME Filed June 15, 1948 4 Sheets-Sheet 5 Ci 1000 81 5000 U] 3 J3, 3 5 '4000 FE 8 O Phenolic resin alone 3 X Plus 10% Sulfur 5 2000 A k u 2O /0 Phenolic Resin,

INVENTORS John 6. Me i Zer' 6 Karl 5. B01 Zerslav BY M W Hi i rs.

May 2, 1950 Filq June 15, 1948 J. G. MEILER ET AL 2,505,782

SULFUR CONTAINING MOLDING COMPOSITIONS, SULFUR CONTAINING CONSOLIDATED PRODUCTS, AND METHOD OF MAKING THE SAME 4 Sheets-Sheet 4 O Phenolic resin alone,

It lus Sulfur- A D II I 5 IO I5 3Q PhznoZ ic Resin INVENTORS John G.Mei 161' 6 Karl E. Bollernslev Patented May 2, 1950 SULFUR CONTAINING MOLDING COMPOSI- TIONS, SULFUR CONTAINING CONSOLI- DATED PRODUCTS, AND METHOD OF MAKING THE SAME John G. Mailer and Karl E. Bollerslev, Tacoma,

Wash, assignors to Plywood Research Foundation, Tacoma, Wash, a corporation of Washington Application June 15, 1948, Serial No. 33,008

14 Claims.

The present invention relates to sulfur containing molding compositions, to sulfur contain ing consolidated products, and to a method of making sulfur containing consolidated products. More particularly, the invention pertains to mold ing compositions adapted for use in the production of composite board products which compositions comprise finely divided lignocellulose material together with a binder comprising a thermosetting phenol-aldehyde resinous condensation product and sulfur.

In the manufacture of consolidated products and particularly composite boards such as hardboard, panel board, and flooring, it is common practice to consolidate a mixture comprising lignocellulose material and binder by the application of heat and pressure. The thermosetting phenol-aldehyde resinous condensation products, particularly the phenol-formaldehyde resins, frequently are employed as binders in such processes and lead to the production of consolidated produots having very desirable properties of strength and water resistance. The use of these resins as binders is. somewhat limited, however, because of their cost. It therefore would be desirable to provide a phenol-aldehyde type binding composition which may be used in the production of consolidated products having high strength and water resistance, but in which a substantial proportion of the phenol-aldehyde resin has been replaced with a relatively inexpensive material.

We have now discovered that, in molding compositions comprising lignocellulose material and phenol-aldehyde resinous binders, a large proportion, i. e. 50% or more, of the latter may be replaced with elemental sulfur to form compositions which after consolidation by the application of heat and pressure surprisingly and unexpectedly have strength and water resistance qualities which are at least equal to those of consolidated products formed through the agency of binders comprising unextended phenol-aldehyde resins. In addition, the abrasion resistance of the sulfur containing consolidated products is substantially superior to that of the comparable products corrtaining no sulfur. This fact makes the compositions of the invention particularly applicable for use as flooring and in similar applications where they are subjected to abrasive wear These various properties of the consolidated products of the invention are illustrated in the accompanying drawings wherein:

Figure 1 shows the water absorption characteristics of consolidated products of the invention containing varying proportions of phenol-aldehyde resin and sulfur;

Figure 2 shows the swelling characteristics upon exposure to moisture of consolidated products of the invention containing varying proportions of phenol-aldehyde resin and sulfur;

Figure 3 shows the flexural strengths (modulus of rupture in bending) of consolidated products of the invention containing varying proportions of phenol-aldehyde resin and sulfur; and

Figure 4 shows the abrasion resistance as measured by a standard Taber abrasion tester of consolidated products of the invention containing varying proportions of phenol-aldehyde resin and sulfur.

A variety of lignocellulosic materials may be used as base materials in the compositions of the invention. Thus, there may be employed annual products such as corn stalks, corn cobs, straw, sugar cane, etc. as well as the Wood from various species of trees, both hard and soft. The lignocellulose material preferably is in finely divided form, as in the case of sawdust, sander dust, wood fiber, or wood flour.

The phenol-aldehyde resinous condensation products which may be used as primary constituents of compositions for binding together the foregoing and other lignocellulosic base materials comprise the broad class of resins formed by condensing a phenol and an aldehyde in the presence of a suitable catalyst. They include for example the condensation products of phenol and formaldehyde, phenol and furfural, phenol and the substituted furfurals, the cresols and formaldehyde, the xylenols and formaldehyde, resorcinol and formaldehyde and the like. These various condensation products preferably are employed in thqform of their aqueous suspensions and may be used singly or in admixture with each other. They are typified by the Water miscible phenolformaldehyde resinous condensation products marketed under the trade-name Durez 12704, the same being an aqueous suspension containing about by weight solids. They also are typified by the water miscible phenol-formaldehyde resinous condensation product under the trade name of Plyophen 5015, which is an aqueous suspension containing from 68% to 70 by Weight solids.

The sulfur employed to replace a portion of the 'heat and pressure.

phenol-aldehyde resinous condensation products content of the binder may be in the form of elementary sulfur such as is available on the market from any of the usual sources. It preferably should be relatilvely free from contaminating materials and in a finely divided form.

The relative proportions of phenol-aldehyde resin and sulfur are critical in formulating molding compositions having "the properties desired for the purposes of the present invention. too little resin is used, the consolidated products formed from the resulting molding-compositions: do not have the requisite qualitiesof w'aterre sistance and strength. If ofi'thebtherhand'an excessive amount of phenol-aldehyde resin is employed, the molding compositiontendsto' flow and develop a spotty appearance' ewhen subjected to Similarly --if the percentage of sulfur employed is too low, the desirable properties in the consolidated products dei'ivingirom goits use are not appreciably developedl If excessive quantities of sulfur are employed the mold: ing compositions are subject to the same defect as obtains- When excessive quantities'gof phenolaldehyderesin aroused, L e. they tend to ii'owg5 on consolidation to storm consolidated products having a spotty appearance.-

The molding compositionsof. the- -inventionthus comprise from .aboutBO to about 50% byweight: of lignocellulose material and from about to about 50% by weight oflbi-nder, the amount-of binder being in inverseproportion to the amount of: lignocellulosamaterial, and comprising fromabout 10 to-about30% .-by;-weig ht of phenolaldehyde resin (basedion the total weight-of the 5 molding composition'l andnfromabout 5% to about 40 sulfun (based- 0nthe total weight of the-molding. composition) Preferred molding compositions particularlysu-ited for, usein the production of composite board products oomprise from about 30% ton'abou-ti 58% by -weight lignocellulosematerial -andafronr about 20%. to about- %.;by wightbindenthe amount oi binder beinminverselyproportional to the amountof I li'g-nocellulose material, and comprising from: 45 about '10 to about-29%; I phenol' aldehyde resin and from about -10 ito-a bout 20%.- sulfur; "the"- weights of =phenolaldehyde iresin andsulfur=being= based on the total weight 0ftheunoldingmom position. A typical-mold-ingr cornposition oi'tlie 5o inventionmay contain about 65% lignocellulcsematerial,- I 15 phenol-aldehyde resin; and- 15-% to i '20 sulfur, percent being expressed as l per cent by weight In .preparing athe molding compositions =of the present. invention, there pref crab-1y is formed firsta mixture orthe phenol-aldehyde resin thev sulfur. Thisthen is mixed with =the=iinocellulose materiaLfpreferably in -a-batch or conti-nuous type mixer Ofconventional construction? If preferred, however, the sulfurandphenol-- aldehyderesin may .beadded individually- :to the: lignocellulose material. Waterorotheniiuid may be added during the mixing procedure in order to promote the -mix-ing .-process andi-to iacilitata thorough dispersion of the binder throughout;

the mass.- After--the mixingi;is-complete, the finished molding. composition is removed irom the mixer andfii" necessaryfdried to ai -moisture content appropriate for-theparticularmoldinm. operationcontemplated] lf i t istol beused in the productionof composite board, its-moisture con-- tent may .be reeuce rdr example} to a valueof- 1'ss "than about 'by weightl When used in the production of consolidated T5 thickness of about one-quarter inch, pressing it atibetween about 100? C. and about 175 C. at pressures' -of between about 50 pounds per square inch-and*about =500 pounds per square inch for time's"ofbetween'fabout 2 minutes an about 30 minutes'may'be'reciuired. In the usual case, in

order-to produce sueh' a board, it sufiices to press themixture for nbout 7 to 15' minutes at a temperatureot about l25 C. to 165 C. and at a pressure of about' 'l5o to 200 pounds per square inch.

The molding compositions of the invention and theira'ppli'cation in the production of consolidated products are illustrated by the following examples, wherein the percentages -of the constituents are expressed as percent by -weight a p A series "of moldingicompositions was prepared? by mixing sawdust (through 29.;mesh; retained by 89 mesh) with binders containing-from 1%-to 30% of a thermosetting aphenol-formaldehyde; condensationproduct (Pl-yophen- 5615" and Durez 12704) and irom fii to 20% sulfur. The i mixingioperatioirwas carried -outin 'a stirring type i mix-er, in-which thesawdust--was='placed=first, thes previously mixed sulfur and; phenol-iormaldehydeu-resin beingzadded gradual-1y; and-with continuous agitation. Water added -as---- necessary in order to secure uniform-dispersion-oi the binder-throughouathe-massz- After themixing?- was complete; the composition was removed fromthe-mixer and dried to a moisture content of 10 It thenewas-p-lacedin a chase iformibetween; the-platens of a'-p r ess-and. pressed-at -;to (3, andto 200 -poundseper square inch for; fromfl -to 15; minutes; The-resulting boarde Wh-ich hada thickness oi about one-quarterinch;- were-re-movedironr thepress hot V r The board samples prepared as-described abovethen were .-=subjeeted to various-tests to measure their fiexural strength,-water.resistance, and res sistanoe to abrasion; Their flexural strengths-- (modulus-0f rupture in--bending)-- were measured by thestandard test'method iordetermining these-- values.- Their watch-resistance was ;I 1'&Sllldby accurately weighing; andmeasuring samples having approximate dimensions -01 one-half inch by six inches and then soak ing them in water atabou-t 7 5 Fl for'24'hours: The samplesthen wereremoved iromthe water-and-again weighedand measured. The water absor-ption was calculatedasthe' increase in weight, expressedas percent of the original weight,- and the thickness swelling as-the increase in thiclmess expreseednspercent of the orig-inalthickness V 7 The abrasion resistanee ofthe samples was measured by means of a standard =Taber= abrasion, tester employing-wheel#63171; After ten thousand =-revolutions -of. the-wheel the-thickness of the samplewas measured -four pla es- -andathe average averagedifierenceinthickness, expressed? in inches (beforeand; afterabrad-ing): was" determined- V The following :examples --i l-lustratethe molding compositions of {the invention -containing 10-.% -of phenolaldehyderesin together-=with from 0 to 20% sulfur.

The following examples illustrate the molding compositions of the invention containing 15% phenol-aldehyde resin and from 0 to 20% sulfur.

Example Number "I 5 I 6 7 8 Phenol Aldehyde Resin.percent 15 15 15 15 ur do 10 Water Absorption do 42. 7 27. 3 14.3 0. l Swelling (Thickness) .do.--. 8.6 7. 7 4. 4 2. 6 Flexural Strength. .p. s. i. 4, 872 5, 120 7, 590 7, 650 Specific Gravity 0. 74 0.89 0. as 1. 04 Abrasion Resistance "inches; 0.0083 0.0043 0.0054 0.0

The following examples illustrate the molding compositions of the invention containing 20% phenol-aldehyde resin and from 0 to 20% sulfur.

Example Number 0 10 ll 12 Phenol Aldehyde Resinpercent" 20 20 20 20 Sulfur 1o 10 15 20 Water Absorption -.do 35. 4 3. 7 2. 9 2. 5 Swelling (Thickness) do 6.8 1.6 1.3 0.4 Flexural Strength. 7, 900 7, 800 7, 060 8, 050 Specific Gravity 1.06 1.14 1. l3 Abrasion Resistance 0.0053 0.0028 0. 0032 The following examples illustrate molding compositions of the invention containing higher percentages of, phenol-aldehyde resin together with 15 and 20% sulfur.

Example Number u 13 14 l 15 Phenol Aldehyde Resin -.per cent 25 Sulfur --do 15 20 Water Absorption.-. do 1.0 1. 0 5. 2 Swelling (Thickness) .,do 0. 0 0. 0 0.5 Flexura Strength." .4). s. i. 9, 400 9,180 9,000 Specific Gravity 1 1.35 1. 25 0.99 Abrasion Resistance --inches 0, 0025 0. 0010 0. 0019 In a manner similar to that described above in connection with the preparation of the molding compositions of Examples 1 to 15, inclusive, there may be prepared molding compositions and condrawings, that by the incorporation of substantial amounts of sulfur together with a phenolaldehyde resinous binder in accordance with the method of the present invention, the amount of phenol-aldehyde resin used may be reduced very materially, with attendant reduction in cost, but

without sacrificing desirable qualities. The resulting sulfur containing consolidated products have flexural strengths and qualities of water resistance, as great or greater than consolidated products containing no sulfur but higher percentages of phenol-aldehyde resins. As is clearly apparent from the drawings consolidated products containing a binder comprising 15% by weight phenol-aldehyde resin together with from 15% to 20% by weight sulfur are far superior in water resistance and flexural strength to consolidated products having a binder comprising 6 the same amount of phenol-aldehyde resin but without added sulfur. Such sulfurlcontaining, consolidated products are, in fact, the full equivalent ln strength and water resistance of, consolidated products containing as much as 30% phenol-aldehyde resin and no sulfur. In addition, the sulfur containing consolidated compositions have superior abrasion resistance, a

factor which makes them highly useful in certain.

applications, as in theproduction of flooring and similar materials.

Having now described the invention in preferred embodiments, what is claimed as new and desired to protect by Letters Patent is:

1. A molding composition for use in the production of consolidated products having high water resistance, high flexural strength, and high resistance to abrasion which comprises from about to about 50% by weight lignocellulose material and from about 20% to about 50% by weight of binder, the amount of binder being inversely proportional to the amount of lignocellulose material, said binder comprising from about 10% to about 30% by weight of a phenol-adehyde resin, based on the total weight of the molding composition, and from about 5% to about 40% by weight sulfur, based on the total weight of the molding composition.

2. A molding composition for use in the production of consolidated products having high water resistance, high flexural strength, and high resistance to abrasion which comprises from about 80% to about 50% by weight lignocellulose material and from about 20% to about 50% by weight of hinder, the amount of binder being inversely proportional to the amount of lignocellulose material, said binder comprising fromabout 10% to about 30% by weight of a resinous condensation product of phenol and formaldehyde, based on the total weight of the molding composition, and from about 5% to about 40% by weight sulfur, based on the total weight of the molding composition.

3. A molding composition for use in the production of consolidated products having high water resistance, high flexural strength, and high resistance to abrasion which comprises from about 80% to about 50% by weight wood in finely divided form and from about 20% to about 50% by weight of binder, the amount of binder being inversely proportional to the amount of wood,

said binder comprising from about 10% to about 30% by weight of a phenol-aldehyde resin, based on the total weight of the molding composition, and from about 5% to about 40% by weight sulfur, based on the total weight of the moldand from about 10% to about 20% by weight of sulfur, the amounts of phenol formaldehyde resinous condensation product and sulfur being based on the total weight of the molding composition.

5. A molding composition for use in the prouduction of consolidated products having high Wa- --6'.'-'The;me.thoaof liiaking-onsolidated"i i'o which comprises forming: a unix ture ornii from about 80 to ab'out=50% bib weight Hg cellulose: material and --i1 i:iuabout -2022; toabout 50% by weight of binder, the moi-latte bind-?" being inversely iropor tionaito theamount -01" linoc'e'llulose materiai; thebinder computing-be tween about 10% and about:30%' byweight-(of thesaiu: tufe') oi a-fiheii'o "aiueeyda em mq 15 betweei out 5% ana a t-cutie '%-15y weight efj saidrniiture)-of-suliu ndeonsohda tingthe sa Ifiiitiii by the ab'pl'ioa tioi'i of heat ti-rid biessure;

- 7. I-h-method' of making -coiisoiidatedproducts which *oompr'ises iorining a rnixture comijri'sing 1 from about 80 to about 50% by wei ht ligno cellulosemateriai and from about 20 -7}-to*abeiit v 50% by- Weightbf-binder; the amount Of bii'iiii being inversely pioporuonar to the amount of lig-noceiluiose material, the binder comprising bee 5 tween abut j1i)%--and'aboiit 39% by weight (of the said mixture) -of a'bi'ienbbaid'ehyde resin-v an between about %Vand about 40%;.by weight- (of "saidmixture) er sulfur; and consolidating' the saidrnixture bypres'siiig'it at between aboutfiq o and about 50o==1oounds per-square ineh and at between about 125 c: and-a out- 165 c; for e time of between about two minutes and about-130* minutes. V W

8; The method of making consolidatedproduets- Which-comprises forming a' mixture comprising from-about *80%"to about 50%;- by weig'ht lig'no'; cellulose 'mat'eriai and from fabout20 to about" 5 0 by Weight 'ofbinder; "the" amount of *bindeif being inversely-firo'portiona'lto the amount-0i li'gnocelluioseinateriai,the binder o p rism bf tweenabout 19 and about '30 by weight-(based on the total Weight of said inixturerof'a resinous condensation bred-not K of phenol and remade-V hyde and-btWen'aboufi 5% and about 46%- w'eight' (basedon the'tot a1- Weight of said inix true) or"- -su1p=hur',=arid emanat ng the said niix ture by the abhlicaitioi beat and- 13 V 9; The method ofinaki-ng" consolidated i'iroduts which' comprises forixiirig a=-1riixture comprising 5otween abut "10% and about 30 by weight" (based on the total weight of said mixture) of a resinous "condensation roductof-"phenol and formaldehyde and between about %--and about 4G byw e'ight (based onthetotai' Weigi'it oi"- said ao mixture) of-sulfur, and consolidating the sa mixture by pressing at betwee'nabout -1'7'5' poui'i'ds I per square inch about ZGOLpoundsineBsquare inch and at a temperature o'i between Iabout12'5 C-. 5a dabout 16 5: G .-:-fori' a time: of between Labautztmr atbetween about 175;pounds'per square inoh tion p'froduct oiphenol and formaldehydeand be w i ni bi fl nd i -b0 749% bifwiii ht 09a on thetotal .weight, of said mixture) ofsuit and consolidatingvthe said mixture by press about ZOO-pounds persqua're inch and at a tame perajture of, between about 125? Q. and about 7165? C. fora 'timeof between about 7 minutes and about;, 15,minutes. 7 i

V 11 Asianew articleof manufacture}. 1316:0011- solidated product, comprising from about :80 agents to about fifl parts-lignocellulose material andfr eze about20= parts to: about 50 parts by-,w.eight:;-of'

V binder, the amount of binder being-inversely pro portional to the amount of iignoceliuiose maa terial, the binder comprising from between about" 10% to about byweight (of saidV-iiiixture) of phenol-aldehyde resin and between about 5% and about 40%.by weight (of said mixture) of sulfur, said mixture havingibeen consolidated by the appl-icationof heat and pressure.

12.13:; a new articl of manufacture; thecon soiidated product comprising from ab'Qut SO- partS to about parts wood in finely divided form and from about 29 parts to about 50 parts byWeight of binder, the amount of binder "being inversely" iroportional, to the amount oi-wooa, the" binder comprising from between 10% to about 30%b3 weight ,(of said mixture) of phenolaldehyde resin and between, about 5% and about 46 %;-bv' weight (of-said mixture) of sulfur, said mixture having been consolidated. by the application of heat and pressure.

13,-As a' new article of inanufactur e, the con soiidat ed product omp'ris'ing from about 86 party to about 50 parts lignocellulose material and from aboutZQ parts tov about 50 parts by Weight of hinder, the amount of binder being inversely proportional tov the amount of lignoceliulose material, the binder comiciris'ing' froin between about 10% to 1ab0ut:30% byweight (-of said ni-ixturei of airesinouscondensation broduct of phenol and forinalde'hydeand between about 5% and about 49% by' weight oijjsaid inixturejlof sulfur, said mixture having beenconsolidatedby the application'of heat and pressure. v g

14. As anew article of manufacture, the consolid-ated-product comprising a rnixture compris: ingirom aboutto about 50 by weightot wood in finely divided forr'n andbetween about 20% and about; 50%, Pay-weight of-binder, ,;the amount of binder beingi versely proportional to. the amount of wood,the binder comprising 'between about 10% and aboutv2Q% -by weight (of said mixture) of a resinous condensation product Of ;19h1l011,311d formaldehyde and between about 10%. and 20% byweight' (ofsaidmixture) of 5 11- funthezeaidmlxture having been consolidated by being subjectedto a pressure of between about 50 pounds iner-tsqueu'e inchv and about .500 p unds per square inch and a temperature of, between about C.;and about C. for a time of -be-" tween about 2;;minutes and abQutaSO: minutes.

, JOHN .G. MEI-LEE.

- KARLBrzBOLLERSLEV.

, REFEBENGEE Great The following reierenees ase ofrecord in the file or this I patent 

1. A MOLDING COMPOSITION FOR USE IN THE PRODUCTION OF CONSOLIDATED PRODUCTS HAVING HIGH WATER RESISTANCE, HIGH FLUXURAL STRENGTH, AND HIGH RESISTANCE TO ABRASION WHICH COMPRISES FROM ABOUT 80% TO ABOUT 50% BY WEIGHT LIGNOCELLULOSE MATERIAL AND FROM ABOUT 20% TO ABOUT 50% BY WEIGHT OF BINDER, THE AMOUNT OF BINDER BEING INVERSELY PROPORTIONAL TO THE AMOUNT OF LIGNOCELLULOSE MATERIAL, SAID BINDER COMPRISING FROM ABOUT 10% TO ABOUT 30% BY WEIGHT OF A PHENOL-ADEHYDE RESIN, BASED ON THE TOTAL WEIGHT OF THE MOLDING COMPOSITION, AND FROM ABOUT 5% TO ABOUT 40% BY WEIGHT SULFUR, BASED ON THE TOTAL WEIGHT OF THE MOLDING COMPOSITION. 